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When the storm knocks the power out and the fridge starts warming, an open frame generator on the driveway buys time, and that is why the best inverter generator open frame earns a look before the next outage. We compared what each listing states: watts, run times, outlets, protections and warranty terms. The picks below cover portable units and a large whole-home unit, with a title-only listing kept at the end because its listing states less.
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Quick picks
Best Overall Oxseryn 12000W: 12000 starting watts with a 50A outlet and 2-year warranty stated Check price on Amazon
CO Shutoff Listed BILT HARD 4500W: CO auto-shutoff with low-oil shutdown and circuit breakers stated Check price on Amazon
Portable Pick Mutaomay 4400W: 56 pounds with ECO mode and 14 hours at 25% load stated Check price on Amazon
Electric Start WEN GN875i: 8750 surge watts with electric start and four 120V receptacles Check price on Amazon
Remote Start Title Westinghouse 10000W: Remote start in the title, with no further specs stated Check price on Amazon
The kits we chose
| # | Product | Solar Score | Buy |
|---|---|---|---|
| 1 | Oxseryn 12000W | 9.7/10 | Buy on Amazon |
| 2 | Westinghouse ecoGen10000 | 9.7/10 | Buy on Amazon |
| 3 | BILT HARD 4500W | 9.6/10 | Buy on Amazon |
| 4 | Mutaomay 4400W | 9.6/10 | Buy on Amazon |
| 5 | WEN GN875i | 9.5/10 | Buy on Amazon |

Oxseryn 12000W
A 12000W open frame inverter generator with a 50A outlet, ECO mode and a 2-year warranty stated.
Pros
- 12000 starting watts and 9000 running watts stated
- 50A outlet plus four 120V 20A outlets and a 12V DC port
- 10 hours at 50% load on a 6.6-gallon tank stated
- Digital meter showing voltage, frequency and runtime stated
Cons
- Weight listed three ways: 150 lb in the title, 159 lb in the bullets, 150.0 pounds in the spec table
- No remote start stated
- Wheels and folding handle need assembly per the listing note
- No parallel capability stated
Detailed Review
The listing states 12000W starting watts and 9000 running watts, a 6.6-gallon tank, ECO mode, up to 10 hours at 50% load, 77 dB at 23 feet, pure sine wave power for sensitive electronics, one 120V/240V 50A outlet, four 120V 20A outlets, one 12V DC port, a digital meter, a fuel gauge, protective outlet covers, AC/DC overload protection, a low-oil indicator and a 2-year manufacturer warranty. One contradiction sits inside the listing: the title says 150 lb, the bullets say 159 lb, and the spec table says 150.0 pounds, so no single weight figure is settled. The listing also notes two packages, with the wheels and folding handle needing assembly.
Who it's for: homeowners and large RV owners who need 12000 starting watts with a 50A outlet and a stated warranty term. Who should skip it: shoppers who need a settled weight figure or remote start, since this listing gives neither.
Its Solar Score of 9.7/10 comes from performance 33/35, build 22/25, value 21/25, safety 7/10 and warranty 3/5: 86 of 100 points, placed on our 9.2 to 9.8 scale.
Key Specifications
| Peak watts | 12000 |
|---|---|
| Running watts | 9000 |
| Noise | 77 dB from 23 feet |
| Warranty | 2 years |
Figures as published on the retailer listing, collected 3 November 2026. Performance figures are manufacturer rated.
Safety and Warranty
What this listing states. AC/DC overload protection and low-oil indicator stated, so safety scores 7 of 10. 2-year manufacturer warranty stated. It does not say everything a buyer needs, such as who pays return shipping, so warranty scores 3 of 5. See How We Pick.
Inverter limits. Stay within the stated continuous watts (surge watts last only a moment), use the cable size and fuse the manual gives, ventilate it, and never connect an inverter to home wiring yourself; that is work for a licensed electrician.
This is general buying information, not professional advice. Follow each product manual and local rules, and see our Safety Disclaimer.

Westinghouse ecoGen10000
A 10000 peak watt open frame inverter generator with remote electric start, transfer-switch-ready outlets and up to 12 hours of run time.
Pros
- 10000 peak watts and 7600 running watts at less than 3% THD
- Remote electric start with included key fob, push button and recoil start
- Up to 12 hours of run time on a 5.28 gallon fuel tank
- Four GFCI 120V outlets plus transfer-switch-ready 120V and 120/240V outlets
Cons
- 147.7 pounds, the largest weight stated in this roundup
- No noise figure stated
- No parallel capability stated
- Minimal assembly required out of the box
Detailed Review
The listing states 7600 running watts and 10000 peak watts at less than 3% THD, remote electric start with an included key fob, push button and recoil start, and up to 12 hours of run time on a 5.28 gallon fuel tank with a fuel gauge. It lists four GFCI 120V outlets, one transfer-switch-ready 120V L14-30R outlet and one transfer-switch-ready 120/240V 14-50R outlet, all with rubber covers, plus a heavy-duty 420cc 4-stroke OHV engine with a cast iron sleeve, automatic low oil shutdown, a digital hour meter and a VFT display showing voltage, frequency and lifetime hours. Coverage is a 3-year limited service, labor and parts term with a nationwide customer service network.
Who it's for: buyers who want high output, remote start and transfer-switch-ready outlets for home backup. Who should skip it: anyone who needs a light unit to carry, since this one lists 147.7 pounds.
Its Solar Score of 9.7/10 comes from performance 32/35, build 21/25, value 21/25, safety 8/10 and warranty 4/5: 86 of 100 points, placed on our 9.2 to 9.8 scale.
Key Specifications
| Running Watts | 7600 |
|---|---|
| Peak Watts | 10000 |
| Run Time | Up to 12 Hours |
| Weight | 147.7 pounds |
Figures as published on the retailer listing, collected 3 November 2026. Performance figures are manufacturer rated.
Safety and Warranty
What this listing states. CO sensor, GFCI outlets with rubber covers and automatic low oil shutdown, so safety scores 8 of 10. 3 Year Limited Warranty. It does not say everything a buyer needs, such as who pays return shipping, so warranty scores 4 of 5. See How We Pick.
Inverter limits. Stay within the stated continuous watts (surge watts last only a moment), use the cable size and fuse the manual gives, ventilate it, and never connect an inverter to home wiring yourself; that is work for a licensed electrician.
This is general buying information, not professional advice. Follow each product manual and local rules, and see our Safety Disclaimer.

BILT HARD 4500W
A 4500-watt open frame inverter generator with CO auto-shutoff, Low Idle switch and parallel-ready design.
Pros
- 4500 starting watts and 3500 running watts stated
- CO auto-shutoff with low-oil shutdown and circuit breakers stated
- Low Idle switch adjusts engine speed with load
- LED multi-meter showing voltage, frequency and runtime stated
Cons
- No warranty term stated
- Recoil start only, no electric start stated
- No run time hours stated
- 1.6-gallon tank, the smallest tank figure here
Detailed Review
The listing states a 4-stroke 223cc air-cooled OHV engine with 4500 starting watts and 3500 running watts on gasoline, a recoil-start system, a 1.6-gallon tank, a Low Idle switch, 120V 20A duplex outlets, a 120V 30A twist-lock outlet, a 12V DC outlet, parallel ports for two compatible units with a parallel kit, CO auto-shutoff, low-oil shutdown, overload warning indicators, AC/DC circuit breakers and an LED multi-meter. No run time hours and no warranty term are stated.
Who it's for: campers and homeowners who want CO auto-shutoff with a full protection list in a portable unit. Who should skip it: shoppers who need electric start, stated run time hours or a stated warranty term, since this listing states none of those.
Its Solar Score of 9.6/10 comes from performance 30/35, build 21/25, value 20/25, safety 8/10 and warranty 0/5: 79 of 100 points, placed on our 9.2 to 9.8 scale.
Key Specifications
| Starting watts | 4500 |
|---|---|
| Running watts | 3500 |
| Tank | 1.6 gallons |
| Safety | CO auto-shutoff |
Figures as published on the retailer listing, collected 3 November 2026. Performance figures are manufacturer rated.
Safety and Warranty
What this listing states. CO auto-shutoff, low-oil shutdown, overload warning indicators and AC/DC circuit breakers stated, so safety scores 8 of 10. No warranty term, so warranty scores zero. See How We Pick.
Inverter limits. Stay within the stated continuous watts (surge watts last only a moment), use the cable size and fuse the manual gives, ventilate it, and never connect an inverter to home wiring yourself; that is work for a licensed electrician.
This is general buying information, not professional advice. Follow each product manual and local rules, and see our Safety Disclaimer.

Mutaomay 4400W
A 4400-watt open frame inverter generator with a 30A RV outlet, ECO mode and low-oil shutoff.
Pros
- 4400 starting watts and 3400 running watts stated
- 30A TT-30R RV outlet plus two 120V AC outlets and one 12V DC outlet
- Up to 14 hours at 25% load with ECO mode stated
- 56 pounds with a built-in frame for handling
Cons
- No warranty term stated
- No electric start stated
- No noise level stated
- Height listed two ways: 15.15 inches in bullets against 15.0 inches in the spec table
Detailed Review
The listing states a 208cc OHV engine with 4400 starting watts and 3400 running watts, a 30A TT-30R RV outlet, two 120V AC household outlets, one 12V DC outlet, ECO mode, up to 14 hours of runtime at 25% load, 56 pounds, a built-in frame, low-oil shutdown, overload protection and EPA compliance. One contradiction sits inside the listing: the bullets give 15.15 inches for height, while the spec table gives 15.0 inches, so this article follows the bullets. No warranty term, no start type and no noise level are stated.
Who it's for: campers and homeowners who want a portable 4400-watt unit with a 30A RV outlet and long stated run time at low load. Who should skip it: shoppers who need electric start, a stated noise level or a stated warranty term, since this listing states none of those.
Its Solar Score of 9.6/10 comes from performance 29/35, build 20/25, value 20/25, safety 7/10 and warranty 0/5: 76 of 100 points, placed on our 9.2 to 9.8 scale.
Key Specifications
| Starting watts | 4400 |
|---|---|
| Running watts | 3400 |
| Run time | 14 hours at 25% load |
| Weight | 56 pounds |
Figures as published on the retailer listing, collected 3 November 2026. Performance figures are manufacturer rated.
Safety and Warranty
What this listing states. Low-oil shutdown and overload protection stated, so safety scores 7 of 10. No warranty term, so warranty scores zero. See How We Pick.
Inverter limits. Stay within the stated continuous watts (surge watts last only a moment), use the cable size and fuse the manual gives, ventilate it, and never connect an inverter to home wiring yourself; that is work for a licensed electrician.
This is general buying information, not professional advice. Follow each product manual and local rules, and see our Safety Disclaimer.

WEN GN875i
An 8750-watt open frame inverter generator with electric start, four 120V receptacles and USB ports.
Pros
- 8750 surge watts and 7000 rated watts stated
- Electric start stated
- Four 120V receptacles plus two 5V USB ports
- 120V RV-ready TT-30R receptacle stated
Cons
- No warranty term stated
- No protection list stated
- Weight not stated in the listing
- No low-oil shutdown stated
Detailed Review
The listing states a 420cc 4-stroke OHV engine with 8750 surge watts and 7000 rated watts, clean power for sensitive electronics such as smartphones, tablets, televisions and computers, a 4.2-gallon tank with up to 6.7 hours of half-load run time, electric start, four 120V NEMA 5-20R receptacles, two 5V USB ports, one 120V/240V NEMA L14-30R twist lock receptacle and one 120V RV-ready TT-30R receptacle. It also claims the body weighs 30% less than a traditional 8750-watt generator. No warranty term, no weight figure and no protection list are stated.
Who it's for: shoppers who want electric start with a wide outlet mix including USB ports and an RV receptacle. Who should skip it: shoppers who need a stated warranty term or a stated protection list, since this listing states neither.
Its Solar Score of 9.5/10 comes from performance 32/35, build 21/25, value 21/25, safety 0/10 and warranty 0/5: 74 of 100 points, placed on our 9.2 to 9.8 scale.
Key Specifications
| Surge watts | 8750 |
|---|---|
| Rated watts | 7000 |
| Run time | 6.7 hours half-load |
| Outlets | L14-30R plus TT-30R |
Figures as published on the retailer listing, collected 3 November 2026. Performance figures are manufacturer rated.
Safety and Warranty
What this listing states. No UL or ETL listing and no protection detail is stated, so safety scores zero. No warranty term, so warranty scores zero. See How We Pick.
Inverter limits. Stay within the stated continuous watts (surge watts last only a moment), use the cable size and fuse the manual gives, ventilate it, and never connect an inverter to home wiring yourself; that is work for a licensed electrician.
This is general buying information, not professional advice. Follow each product manual and local rules, and see our Safety Disclaimer.
As an Amazon Associate I earn from qualifying purchases.
More picks to compare
WEN GN400i4000 surge watts with RV-ready outlet and parallel-ready panelCheck on Amazon- Champion 5500W5500-watt open frame inverter generator with recoil start and RV readyCheck on Amazon
Numbers side by side
| Open Frame Generator | Solar Score | Peak Watts | Run Time | Outlets | Warranty | Amazon |
|---|---|---|---|---|---|---|
| Oxseryn 12000W | 9.7/10 | 12000 | 10 hours at 50% load | 50A outlet | 2 years | View on Amazon |
| BILT HARD 4500W | 9.6/10 | 4500 | Not stated | 30A twist-lock | Not stated | View on Amazon |
| Mutaomay 4400W | 9.6/10 | 4400 | 14 hours at 25% load | 30A RV outlet | Not stated | View on Amazon |
| WEN GN875i | 9.5/10 | 8750 | 6.7 hours half-load | L14-30R plus TT-30R | Not stated | View on Amazon |
| Westinghouse 10000W | 9.7/10 | 10000 | Not stated | Not stated | Not stated |
Specifications are manufacturer rated as listed, collected 3 November 2026.
Where the points went
The Solar Score weighs performance, build, value, safety and warranty. For an open frame inverter generator, safety means stated protections such as CO shutoff, low-oil shutdown, overload protection and circuit breakers; a pick that states none scores zero on that line. One of the five picks states a warranty term. How we pick explains the weights.
| Product | Solar Score | Perf. /35 | Build /25 | Value /25 | Safety /10 | Warranty /5 |
|---|---|---|---|---|---|---|
| Oxseryn 12000W | 9.7 | 33 | 22 | 21 | 7 | 3 |
| BILT HARD 4500W | 9.6 | 30 | 21 | 20 | 8 | 0 |
| Mutaomay 4400W | 9.6 | 29 | 20 | 20 | 7 | 0 |
| WEN GN875i | 9.5 | 32 | 21 | 21 | 0 | 0 |
Scores run from 9.2 to 9.8: each product’s point total is placed on that range, so more points always means a higher score.
How to choose the best inverter generator open frame
Match watts to the load
The Oxseryn unit lists 12000 starting watts and 9000 running watts, while the WEN unit lists 8750 surge watts and 7000 rated watts. The BILT HARD unit lists 4500 starting watts and 3500 running watts, and the Mutaomay unit lists 4400 starting watts and 3400 running watts. The Westinghouse title lists 10000 peak watts with no running watts stated. Add up the running watts of the loads you plan to run, then check the running watts line, not just the peak figure.
| Generator | Starting watts | Running watts |
|---|---|---|
| Oxseryn 12000W | 12000 | 9000 |
| BILT HARD 4500W | 4500 | 3500 |
| Mutaomay 4400W | 4400 | 3400 |
| WEN GN875i | 8750 surge | 7000 rated |
| Westinghouse 10000W | 10000 peak | Not stated |
Check outlets before watts
The Oxseryn unit lists one 120V/240V 50A outlet, four 120V 20A outlets and one 12V DC port. The WEN unit lists four 120V NEMA 5-20R receptacles, two 5V USB ports, one 120V/240V NEMA L14-30R twist lock receptacle and one 120V RV-ready TT-30R receptacle. The BILT HARD unit lists 120V 20A duplex outlets, a 120V 30A twist-lock outlet and a 12V DC outlet. The Mutaomay unit lists a 30A TT-30R RV outlet, two 120V AC household outlets and one 12V DC outlet. A licensed electrician should install any transfer switch side of the setup.
Weigh run time against tank size
The Oxseryn unit lists up to 10 hours at 50% load on a 6.6-gallon tank, while the WEN unit lists up to 6.7 hours of half-load run time on a 4.2-gallon tank. The Mutaomay unit lists up to 14 hours at 25% load with ECO mode, but states no tank size. The BILT HARD unit lists a 1.6-gallon tank with no run time hours stated. A stated run time without a stated load means less than a run time tied to a load figure, so compare the load lines together. For home backup use, see our inverter generator for home backup guide.
Run it outdoors
Fuel generators run outdoors only, far from doors and windows, because of carbon monoxide. The BILT HARD unit lists CO auto-shutoff among its safety features.
Sizing Notes
- Match watts to the load: 12000 starting watts on the Oxseryn unit against 4400 starting watts on the Mutaomay unit.
- Match outlets to the plugs: a 50A outlet on the Oxseryn unit against a 30A RV outlet on the Mutaomay unit.
- Match run time to the tank: 10 hours at 50% load on a 6.6-gallon tank for the Oxseryn unit, and 6.7 hours of half-load run time on a 4.2-gallon tank for the WEN unit.
- Check the warranty term: 2 years on the Oxseryn unit, with no term stated on the other picks.
FAQ: power away from the grid
Which pick here lists the highest starting watts?
The Oxseryn unit, with 12000 starting watts and 9000 running watts. The next highest pick is the WEN unit, with 8750 surge watts and 7000 rated watts.
Which pick here lists CO shutoff?
The BILT HARD unit, which lists CO auto-shutoff alongside low-oil shutdown, overload warning indicators and AC/DC circuit breakers.
Which pick here states a warranty term?
The Oxseryn unit, which states a 2-year manufacturer warranty in its spec table. The other four picks state no warranty term.
Which picks list electric start?
The Oxseryn unit, whose title names electric start, and the WEN unit, which lists electric start in its bullets. The BILT HARD unit lists a recoil-start system, and the Mutaomay listing states no start type.
What size inverter generator for 30 amp RV?
The Mutaomay unit lists a 30A TT-30R RV outlet with 4400 starting watts. The WEN unit lists a 120V RV-ready TT-30R receptacle with 8750 surge watts.
Related solar guides
See every Inverter and Dual Fuel Generators guide and all Power Stations and Generators guides. Also see our best inverter generator for home backup. Also see our best quiet generator for RV.
More picks: gas generator for camping, generators for camping trailers, value generator for RV.




